Hand-held power tool with guard, in particular an angle grinder
The invention relates to a portable power tool for a rotating, preferably disk-shaped tool (12). Said portable power tool comprises a machine housing (14), having a flange (16, 160) or a machine neck, and a protective hood (18) that can be detachably tensioned on the machine neck to cover the tool (12) or that has a protective hood neck (20) or protective hood collar that annularly carries a tightening strap (22). Said strap can be tightened by tensioning means (24). An anti-rotation lock effective between the machine neck and the protective hood (18) is interposed between the protective hood (18) and the machine neck in the form of a profiled structure (26). The invention is characterized in that the tensioning means (24), in its tensioned position, can be connected several times in a form fit to the machine neck and in its detached positioned is no longer connected in a form fit to the machine neck.
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The invention described and claimed hereinbelow is also described in German Patent Applications DE 10 2006 053 304.6 filed on Nov. 13, 2008 and DE 10 2007 041 840.1 filed on Sep. 3, 2007. These German Patent Applications, whose subject matter is incorporated here by reference, provide the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).
BACKGROUND OF THE INVENTIONThe present application is related to a hand-held power tool with a guard.
An angle grinder with an adjustable guard is made known in EP 0 812 657 A1. In that case, the guard is adjustable in a rotating manner on a connection piece of a flange of the angle grinder, and is supported such that it may be detachably attached using a single form-fit locking means. The spindle of the angle grinder passes through the center of the flange. A cutting and/or grinding disk is installed on the free end of the spindle in a clampable, rotationally drivable manner for cutting and machining work pieces, which are partially enclosed by the guard. The guard must be positioned in a rotationally adjustable manner on the hand-held power tool such that the region of the grinding disk that faces the user is enclosed by the guard. At the same time, a region of the grinding disk that points away from the user extends past the flange, radially relative to the work piece engagement.
SUMMARY OF THE INVENTIONThe present invention relates to a hand-held power tool for a rotating, preferably disk-shaped tool, with a machine housing that includes a flange and/or a machine neck, and with a guard that is detachably clampable to the machine neck, for covering the tool, and that includes a guard neck and/or a guard collar with an annular clamping band that may be tightened using a clamping means, and with an anti-rotation lock being located between the guard and the machine neck that is designed as a profiled structure and acts between the machine neck and the guard.
It is provided that the clamping means, in its clamping position, may be connected repeatedly and in a form-fit manner with the machine neck and, in its release position, is disengaged from the form-fit connection with the machine neck. The result is to advantageously ensure a secure connection between the guard and the machine neck of the machine housing that may withstand strong loads that occur during a working process. The guard is preferably prevented from rotating via the profiled structure during operation of the hand-held power tool, thereby ensuring that the guard safely protects the operator, in particular if the tool—a grinding disk, in particular—should burst. The guard may be used in general with hand-held power tools that include a rotating, preferably disk-shaped tool, such as a grinding disk, a cutting disk, and/or a polishing disk, and is usable—particularly advantageously—with an angle grinder.
In this context, a “flange and/or a machine neck” refers to a region of the hand-held power tool that serves to accommodate and/or attach the guard to the hand-held power tool, and that encloses the tool at least partially. This flange and/or machine neck may be designed as a single piece with the hand-held power tool, or it may be designed as a separate component. A “guard connection piece and/or guard collar” located on or integrally formed with the guard preferably refers, in this context, to a region that preferably extends perpendicularly to a main extension plane of the guard, which is provided for attachment with the hand-held power tool and/or for placement on a subregion of the hand-held power tool, in particular on a flange and/or machine neck of the hand-held power tool. This guard connection piece and/or guard collar is advantageously designed as a single piece with a body of the guard. In this context, a “clamping band” refers to a band, and particularly advantageously to a metal band, that bears around a subregion of the guard, e.g., a guard connection piece, in particular in order to attach the guard to the hand-held power tool, and that encloses the subregion in a non-positive and/or form-fit manner with a clamping force in particular. A “clamping means” refers, in particular, to a means that reduces a circumference, in particular of the clamping band, using a clamping process, e.g., the folding down of a lever, the tightening of a screw, or by using another process that appears suitable to one skilled in the technical art. A “profiled structure” refers, in particular, to a shape, e.g., a perforated structure, an edge, and/or an internal pressed-out region, that includes a profile and/or a contour whose geometry depends on a function of the anti-rotation lock. Another type of anti-rotation lock that appears reasonable to one skilled in the art is also feasible, however. In this context, a “clamping position” refers to a position of the clamping band in which the clamping band enters into a connection with a further component that is under mechanical tension, in particular, e.g., a connection based on a form fit, e.g., with the flange and/or the machine neck of the hand-held power tool in particular. A released position therefore refers to a position of the clamping band in which a clamped connection between the clamping band and the further component has been released.
Further advantages result from the description of the drawing, below. Exemplary embodiments of the present invention are shown in the drawing. The drawing, the description, and the claims contain numerous features in combination. One skilled in the art will also advantageously consider the features individually and combine them to form further reasonable combinations.
A hand-held power tool 10 designed as an angle grinder is shown in
An orientation spring 62 is located in a region 88 of flange 16 that has a smooth contour and does not have a toothed profile in circumferential direction 76. Orientation spring 62 serves to establish an exactly defined insertion position of guard 18 relative to flange 16 when guard 18 is installed. To this end, orientation spring 62 is designed as a bent spring-steel lamella. To support orientation spring 62 on flange 16, orientation spring 62 includes two bearing elements 92 in end regions 90. Bearing elements 92 are located in end regions 90 of orientation spring 62 such that they extend outwardly in radial direction 86 (see
Clamping means 24—when in a clamped position—may be connected repeatedly and in a form-fit manner with flange 16, which is designed as the machine neck (
Rocker 40 and latch 42 include undercut-engagement means 32, 60 that are formed by a toothed profile 34, which, together with counter-toothed profile 36 of flange 16, forms profiled structure 26. Toothed profile 34 is provided for engagement in counter-toothed profile 36 and/or in recesses 38 of flange 16 to establish a non-rotatable, form-fit connection between guard 18 and flange 16. Undercut-engagement means 32, 60 and/or toothed profile 34 are/is located on a side 122 of latch 42 and/or rocker 40 facing flange 16. Rocker 40 includes three undercut-engagement means 32, and latch 42 includes two undercut-engagement means 60 (
Undercut-engagement means 60 of latch 42 extend through recess 124 and form, together with counter-toothed profile 36 of flange 16, a form-fit connection when in a clamping position (
Guard 18 may be locked in a fixed position on flange 16 via toothed profile 34, which engages in counter-toothed profile 36 of flange 16 when guard 18 is installed. In addition, an operator may select an installation position in circumferential direction 76 that provides him with maximum protection. Given that counter-toothed profile 36 of flange 16 is limited in circumferential direction 76 to a range of approximately 270°, counter-toothed profile 36 serves as a coding means, thereby ensuring that guard 18 is not installed on flange 16 in a non-permitted position and preventing toggle joint system 44 from closing in region 88 that does not have a counter-toothed profile 36.
If tool 12 should burst, airborne tool particles act forcefully on a guard edge 148 and guard 18. Pulling and rotational forces therefore act on guard 18, but guard 18 is prevented from rotating due to the form-fit connection between clamping means 24 and flange 16. In addition, the pulling forces on guard 18 and clamping band 22 act radially outwardly, thereby causing latch 42 and rocker 40 and/or toothed profile 34 to engage more tightly in recesses 38 and/or counter-toothed profile 36 of flange 16, thereby creating a lock that acts dynamically with increasing strength and serves as a highly effective anti-rotation lock.
A closing force and/or clamping force of clamping band 22 together with clamping means 24 may also be adjusted by an operator. A clamping band length may therefore also be adjusted, e.g., to compensate for production tolerances. To this end, clamping band 22 includes a semi-loop 46, which is realized in circumferential direction 76 by a contour of clamping band 22 that is bent radially outwardly and then radially inwardly (
Alternative exemplary embodiments are shown in
An alternative design of orientation spring 150 is shown in
Claims
1. A hand-held power tool for rotatably driving a disk-shaped tool, comprising:
- a motor to produce a drive torque to drive said disk-shaped tool;
- a spindle to transfer said drive torque from said motor to said disk-shaped tool for rotatably driving said disk-shaped tool around a spindle axis of said spindle;
- a machine housing that comprises a flange embodied as a machine neck that is fixedly connected to said machine housing; and
- a guard for covering said disk-shaped tool;
- wherein said guard comprises a guard neck embodied as a guard collar and an annular clamping band that is located on said guard collar and that comprises a clamping means for detachably clamping said guard to said machine neck, the clamping band extends in annular fashion from a first end around an arc to a second end, wherein there is an open area between the first end and second end void of the clamping band, the clamping band also having a through hole along the arc portion,
- wherein said clamping band is tightenable along a circumferential direction of said guard collar using said clamping means,
- wherein said circumferential direction extends—in a mounted state of said guard—in a plane perpendicular to said spindle axis of said spindle,
- wherein said clamping means comprises at least one pivotal clamping lever that comprises at least two sets of engagement means embodied as two toothed profiles,
- wherein said flange embodied as said machine neck comprises a toothed profile embodied as recesses extending on a circumference of said machine neck facing said guard collar in a mounted state of said guard,
- wherein said recesses of said machine neck are correspondingly formed to said toothed profile of said at least one clamping lever,
- wherein one of said toothed profiles of said at least one clamping lever is provided for engaging into the open area of the clamping band and into said recesses of said machine neck and the other of said toothed profiles of said at least one clamping lever is provided for engaging into the through hole of the clamping band and into said recesses of said machine neck to form an anti-rotation lock between said guard and said machine neck in a form of a profiled structure, and
- wherein said clamping means, in its clamping position, is connected in a form-fit manner with said machine neck and, in its releasing position, is disengaged from the form-fit connection with said machine neck.
2. The hand-held power tool as recited in claim 1, wherein said clamping means comprises a first clamping lever and a second clamping lever which are pivotally connected to each other via a bearing element, wherein said first clamping lever is embodied as a rocker and wherein said second clamping lever is embodied as a latch.
3. The hand-held power tool as recited in claim 2, wherein the rocker and the latch are provided with several holes (50) in order to reduce weight and improve their grippability.
4. The hand-held power tool as recited in claim 2, wherein the first damping lever and the second clamping lever together form a toggle joint system.
5. The hand-held power tool as recited in claim 4, wherein said clamping band comprises at least two clamping band elements, which are provided for adjusting said clamping force of said toggle joint system using said adjusting element.
6. The hand-held power tool as recited in claim 1, wherein said clamping band comprises a bent, projecting semi-loop and an adjusting element that passes through said semi-loop to adjust a clamping force of said clamping band by using said adjusting element.
7. The hand-held power tool as recited in claim 1, wherein said guard collar comprises embossed regions to form embossments along a circumferential direction of said guard collar on a side of said guard collar facing said clamping band, wherein said embossments are provided to engage In recesses of said clamping band which correspond to said embossments and which are located on a side of said clamping band facing said guard collar—in a mounted state of the clamping band on said guard collar.
8. The hand-held power tool as recited in claim 1, wherein said toothed profile of said at least one clamping lever and said corresponding recesses generate a clamp tightening and/or retightening effect when rotational forces act on said guard.
9. The hand-held power tool as recited in claim 1, further comprising an orientation spring, wherein said orientation spring is located on said flange embodied as said machine neck, to which an indentation of said clamping band extending in a radial direction of said clamping band is assigned, wherein said indentation serves as guidance when said guard is inserted axially onto said machine neck.
10. The hand-held power tool as recited in claim 1, wherein, when said guard is rotated in a mounted state, said orientation spring interacts in an overlatching manner with said embossments of said guard collar.
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Type: Grant
Filed: Sep 20, 2007
Date of Patent: Mar 22, 2011
Patent Publication Number: 20090029635
Assignee: Robert Bosch GmbH (Stutggart)
Inventors: Cornelius Boeck (Kirchheim), Joachim Schadow (Leinfelden-Echterdingen), Sinisa Andrasic (Schoenaich)
Primary Examiner: Eileen P. Morgan
Attorney: Michael J. Striker
Application Number: 12/279,883
International Classification: B24B 23/00 (20060101); B24B 55/04 (20060101);